Activity for the week of 17 April-23 April 2002

The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network.

New Activity / Unrest

The Darwin VAAC stated on 24 April that reports of an eruption at Lamington on 22 April were false. Based on information from Geoscience Australia and satellite imagery, the Darwin VAAC originally reported that an E-drifting ash cloud from Lamington seemed to be evident on satellite imagery on 22 April at 1741. Thunderstorms near the volcano made it difficult to locate possible ash on satellite imagery. On 23 April at 1135 a flight service reported that no volcanic activity was observed at Lamington. A team from the Rabaul Volcano Observatory is investigating rumors of activity at the volcano.

Increases in volcanic and seismic activity at Lokon-Empung led VSI to raise the Alert Level from 2 to 3 (on a scale of 1-4) on 12 April. Eruptions occurred on 10 April at 2302 and on the 12th at 1816. On 13 April eight gas-and-ash explosions occurred and on the 14th five occurred. Tremor that began on 11 April continued through at least the 14th.

Ongoing Activity

During 14-18 April, a dense ash plume persisted at the SE vent of Etna's Bocca Nuova crater. Dense ash-free plumes rose above Voragine and Northeast craters. Earthquakes continued on Etna's SE flank, and there were reports of seismicity on the NE flank.

A pilot reported observing an ash cloud from an explosion at Karymsky on 15 April at 1115 that rose 3 km above the volcano. During 12-19 April, seismicity was above background levels and its character indicated that weak ash-and-gas explosions, gas blow-outs, and debris avalanches possibly occurred. Thermal anomalies were visible on AVHRR satellite imagery. The volcano remained at Concern Color Code Yellow ("volcano is restless").

During 18-22 April, surface activity was visible at a minimum of two vent areas of Pu`u` O`o's crater and at the rootless shields. No surface lava flows were visible on Pulama pali. Generally, tremor at Pu`u` O`o was low and only a few small earthquakes and low-level tremor occurred at Kilauea's caldera. During the report period, slow, small deflations occurred at Pu`u` O`o and the caldera.

During 12-19 April, gas-and-steam and ash-and-gas emissions occurred at Shiveluch and seismicity remained above background levels. A short-lived explosive eruption on 15 April at 1906 produced an ash-and-gas plume that rose 1 km above the volcano. Seismicity during the report period included earthquakes with magnitudes less than or equal to 2.3 at depths of 0-5 km, many local shallow seismic signals (from possible avalanches or weak gas-and-ash explosions), and episodes of weak intermittent volcanic tremor. Thermal anomalies were visible on AVHRR satellite imagery, but ash was not. Shiveluch remained at Concern Color Code Yellow ("volcano is restless").

During 12-19 April, the level of volcanism at Soufrière Hills slightly decreased in comparison to the previous week. Lava-dome growth was concentrated on the SE area of the dome complex, although small rockfalls occurred in other areas. The lava dome evolved from a large striated lobe at the beginning of the week, to a series of small spines by week's end. Small, low-level ash clouds were occasionally visible on satellite imagery.

Use the dropdowns to choose the year and week for archived Weekly Reports.

Year

Week

News Feeds and Google Placemarks

The RSS (Really Simple Syndication) feed is identical to the Weekly Volcanic Activity Report minus some features including the header information (latitude and longitude and summit elevation), the Geologic Summary, and a link to the volcano's page from the Global Volcanism Program. Each volcano report includes a link from the volcano's name back to the more complete information in the Weekly Volcanic Activity Report on the Smithsonian website.

The CAP (Common Alerting Protocol) feeds are XML files specifically formatted for disaster management. They are similar in content to the RSS feed, but contain no active links.

A Google Earth network link for the Weekly Volcanic Activity Report can be loaded into the free Google Earth software, and in turn will load placemarks for volcanoes in the current weekly report. Placemark balloons include the volcano name, report date, report text, sources, and links back to the GVP volcano page for that volcano and to the complete Weekly Report for that week.

Criteria & Disclaimers

Criteria

The Weekly Volcanic Activity Report does not necessarily include all volcanic activity that occurred on Earth during the week. More than a dozen volcanoes globally have displayed more-or-less continuous eruptive activity for decades or longer, and such routine activity is typically not reported here. Moreover, Earth's sea-floor volcanism is seldom reported even though in theory it represents the single most prolific source of erupted material. The Weekly Volcanic Activity Report summarizes volcanic activity that meets one or more of the following criteria:

- A volcano observatory raises or lowers the alert level at the volcano.
- A volcanic ash advisory has been released by a volcanic ash advisory center (VAAC) stating that an ash cloud has been produced from the volcano.
- A verifiable news report of new activity or a change in activity at the volcano has been issued.
- Observers have reported a significant change in volcanic activity. Such activity can include, but is not restricted to, pyroclastic flows, lahars, lava flows, dome collapse, or increased unrest.

Volcanoes are included in the "New Activity/Unrest" section of the Weekly Volcanic Activity Report if the activity occurs after at least 3 months of quiescence. Once a volcano is included in the "New Activity/Unrest" section, updates will remain in that section unless the activity continues for more than 1 month without escalating, after which time updates will be listed in the "Continuing Activity" section. Volcanoes are also included in the "New Activity/Unrest" section if the volcano is undergoing a period of relatively high unrest, or increasing unrest. This is commonly equal to Alert Level Orange on a scale of Green, Yellow, Orange, Red, where Red is the highest alert. Or alert level 3 on a scale of 1-4 or 1-5.

It is important to note that volcanic activity meeting one or more of these criteria may occur during the week, but may not be included in the Weekly Volcanic Activity Report because we did not receive a report.

Disclaimers

1. The Weekly Volcanic Activity Report is intended to provide timely information about global volcanism on a weekly basis. Consequently, the report is generated rapidly by summarizing volcanic reports from various sources, with little time for fact checking. The accuracy of the Weekly Volcanic Activity Report is dependent upon the quality of the volcanic activity reports we receive. Reports published in the Bulletin of the Global Volcanism Network are monthly, and more carefully reviewed, although all of the volcanoes discussed in the Weekly Volcanic Activity Report are not necessarily reported in the Bulletin. Because of our emphasis on rapid reporting on the web we have avoided diacritical marks. Reports are updated on the Weekly Volcanic Activity Report web page as they are received, therefore information may be included regarding events that occurred before the current report period.

2. Rapidly developing events lead to coverage that is often fragmentary. Volcanoes, their eruptions, and their plumes and associated atmospheric effects are complex phenomena that may require months to years of data analysis in order to create a comprehensive summary and interpretation of events.

3. Preliminary accounts sometimes contain exaggerations and "false alarms," and accordingly, this report may include some events ultimately found to be erroneous or misleading.

4. Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source.

5. USGS Disclaimer Statement for this Website:

Information presented on this website is considered public information and may be distributed or copied. Use of appropriate byline/photo/image credit is requested. We strongly recommend that USGS data be acquired directly from a USGS server and not through other sources that may change the data in some way. While USGS makes every effort to provide accurate and complete information, various data such as names, telephone numbers, etc. may change prior to updating. USGS welcomes suggestions on how to improve our home page and correct errors. USGS provides no warranty, expressed or implied, as to the accuracy, reliability or completeness of furnished data.

Some of the documents on this server may contain live references (or pointers) to information created and maintained by other organizations. Please note that USGS does not control and cannot guarantee the relevance, timeliness, or accuracy of these outside materials.

For site security purposes and to ensure that this service remains available to all users, this government computer system employs software programs to monitor network traffic to identify unauthorized attempts to upload or change information, or otherwise cause damage. Unauthorized attempts to upload information or change information on this website are strictly prohibited and may be punishable under the Computer Fraud and Abuse Act of 1986 and the National Information Infrastructure Protection Act. Information may also be used for authorized law enforcement investigations. (Last modified September 21, 1999.)

An RSS (Really Simple Syndication) feed for the Weekly Volcanic Activity Report first made available on 5 March 2008 can be utilized with the aid of various free downloadable readers. The report content of the news feed is identical to the Weekly Volcanic Activity Report minus some features including the header information (latitude and longitude and summit elevation), the Geologic Summary, and a link to the volcano's page from the Global Volcanism Program. Each volcano report includes a link from the volcano's name back to the more complete information in the Weekly Volcanic Activity Report on the Smithsonian website. On 12 March 2009, GeoRSS tags were added so that the latitude and longitude for each volcano could be included with the feed.

At the end of each individual report is a list of the sources used. We would like to emphasize that the World Organization of Volcano Observatories (WOVO) website (http://www.wovo.org/) lists the regional volcano observatories that have the most authoritative data for many of these events.

A Google Earth network link for the Weekly Volcanic Activity Report was first made available on 1 April 2009. This file can be loaded into the free Google Earth software, and in turn will load placemarks for volcanoes in the current weekly report. Placemark balloons include the volcano name, report date, report text, sources, and links back to the GVP volcano page for that volcano and to the complete Weekly Report for that week.